The effect of alpha-tocopherol on neurons in protecting against radical-induced injuries caused by cumene hydroperoxide was assessed using a culture system. Structural and biochemical deteriorations in both clonal neuroblastoma cells and primary cultured neurons were induced by cumene hydroperoxide. These deteriorative changes were prevented prevented by pretreatment of alpha-tocopherol. Since simultaneous supplementation of alpha-tocopherol and cumene hydroperoxide had limited protective effects, prophylactic administration of alpha-tocopherol for risk patients with brain diseases concerned with damages induced by free radical is recommended to hamper the progression of neuronal impairment after attacks.